Road construction



Oct. 14, 1941. C'. u. GRAMELSPACHER 2,259,374

ROAD CONSTRUCTION Filed oct. 8, 1958 2 sheets-sheet 1 uapnce Duessm 7Tau. on. O\\

5TONE ov. CoNcle-rs EHQTH Wonu BED- INVENToe 0t 14, 1941. c. u.GRAMELsPAcHER 2,259,374

ROAD CONS TRUCTION Filed Oct. 8, 1958 2 Sheets-Sheet 2 Cmnmce U.GnaMiLsPacHm Patented Oct. 14, 1,941

AUruTeo STATES PATENT OFFICE '1 Claim.

This invention Vrelates to the construction of roads and pavements, andmore particularly to a road or pathway constructed of wood or timber inthe form of plies, together with an appropriate binder and llermaterial.

The invention consists in providing a road or pavement of b-uilt-uplayers comprising a rigid waterproof base with plywood laid thereon toform the body of the roadway with a mastic waterproof surface coatingcovering the top and sides of the plywood.

Wood in the form of blocks has been used heretofore in the constructionof pavements. In this type of pavement construction, however, wood'blocks are exposed directly to the Wear of trafiic as well as thesurrounding climatic conditions.

The wood block is usually treated with creosote oil to preserve the woodand prevent the absorption of water which causes swelling. Treated wood,however, will absorb some water and only i* by thorough and propertreatment can this be reduced in amount so as to obviate trouble fromswelling.

Aside from the difficulties encountered by swelling, wood blockpavements exhibit a high degree of slipperiness when wet which is veryobjectionable. Bituminous bonded road surfaces, asphalt pavements andthe like are superior to Wood in this respect but are inferior to woodin the resistance offered to wear under heavy traffic conditions.Further, due to the pushing force or pressure exerted against thesurface of asphalt or bituminous pavements, by motor vehicle trafc,distinct waves or bumps are produced. Sometimes this occurs in recentlybuilt pavements. To overcome this defect various methods have beendevised involving a more careful selection of materials and moreexpensive road construction, but the problem has not been entirelysolved.

This invention overcomes these defects and provides a highly improvedroad or pavement construction.

An object of this invention is to provide an improved pavement or roadconstruction which is inexpensive to build, highly resistant todistortion under traffic, and very durable.

Another object of this invention is to provide an improved roadway orpavement which utilizes the combination of wood and a suitable surfacedressing to produce a highly improved, inexpensive roadway or pavement.

Another object is to provide a road wherein the body of the highwaysurface comprises plywood. Such a roadway is highly resistant to impactand surface distortion and raveling commonly observed in bituminousaggregate constructed roads and pavements.

Another object is to provide a roadway having laminated wood slabspositioned beneath the traveled surface of the highway in order to pro--d-uce an antirippling roadway.

the drawings:

Figure 1 'is a perspective view of the construction' of V-the roadwayshowing the diiferent layers ithereof;

VFigure -2 is a cross sectional view of the roadway 'orpavementconstructed according to this in vention;

Fig-ure `Bjis an elevation view of the road surface prior -to applyingthe surface dressing;

Eig-ure 4 `is -a View similar to Figure '3, illustrat- :ing `the cuttingand laying of the timber employed;

rFigure 5 is a fragmentary view in section of the plywood sheet or blockemployed, showing the cross grain arrangement of the diiferent plies;

Figure 6 Vis a sectional view of a modified road construction similar tothat illustrated in Figure 2, with certain parts broken away.

Referring to the drawings in detail, the numeral 1 designates a roadbedwhich is shaped to conform to the surface of the finished roadway orpavement. Over the roadbed is applied a waterproof coating 8 of tar, oilor the like. Any waterproofing substance may be employed, but preferablya tar or heavy oil product of coal gas, water gas or coke oven is used.Creosote oil or equivalent heavy oil may be employed either alone ormixed with tar. A mixture of tar and creosote oil is somewhat superioras a waterproofing agent to either of these substances alone.

After the application of a waterproof coating to the roadbed surface, alayer of stone or concrete 9 is applied thereover of desired thicknessand then another waterproofing layer 8 of tar, oil, or a mixturethereof, is disposed over the surface of stone or concrete. This sealsthe concrete, rock or stone section against the penetration of moistureor seepage of water from surrounding earth. Upon the waterproof layer 8is placed a sheet 0r covering I of building paper, libre, plastic orpulp board in order to present a smooth, regular surface forming acushion for the plywood slabs Il laid thereon. In some instances thepaper or libre board covering may be omitted. As an alternative thecushion layer I0 may comprise a bituminous mastic of hot tar or asphaltmixed with sand. Sand may be omitted and tar alone used as anothermodificationl The plywood slabs II, as shown in Figure 5, comprisealternate cross-grained laminated plies of relatively thin sheets ofwood IIa held together by glue or resinous material I2 conventionallyemployed for this purpose. For providing greater rigidity the centralplies can be made thicker than the outer sheets. The dimensions of theplywood slabs may be varied; in general, however, they are of sufficientwidth to extend across substantially one-half the roadway surface. Twosuch slabs are laid with their ends abutting together at or near thecenter of the road as shown in Figures 1 to 4, and covered with surfacedressing. Due to the crossgrained laminated construction of the ply-,-Y

wood expansion of the slabs is compensated for and no special jointsneed be provided. Therplywood slabs may be laid eitherY Yparallelto thecurb, similar to the manner of laying brick, or diagonally, asillustrated in Figures 3 and 4, re-

spectively. f Y

' Over the layer of plywood is ap'plied a surface dressing I3 ofbituminous bonded aggregate. Mineral aggregate employed for this purposeAmay be crushed stone, slag, gravel, grout, and the like, the particlessmaller than l@ inch in diameter being omitted. Preferably aggregatehaving particles ranging in size from 1/2 to 1% inchesin diameter isused. A surface dressing of hot bitumen or asphalt mixed with coarsesand may be applied directly over the plywood ifr desired with orAwithout the use of other ag gregate. This construction makes thepavement thoroughly waterproof and provides for somel slight expansionof the wood inlaid therein.

The wood or'timber plies making up the plywood are preferably treatedwith preservative, such as copper sulphate, zinc chloride, bichloride ofmercury and creosote to prevet the attack of .wood destroying fungi andinsects.

In the modification shown in Figure 6 the outer margins of the plywoodslabs abut against a concrete shoulder I4 which may be extended to formthe curb and gutter adjacent the roadway or pavement. The space betweenthe outer edges of the plywood II and the concrete shoulder I4, as atI5, will be filled with tar or the surface dressing I3 employed to coverthe plywood in the construction shown in Figures 1 and 2. In this waythe plywood will be thoroughly sealed from the atmosphere and maintainedwaterproof.

As a further modification the surface coating I3 may comprise concreteor brick. If desired a combination of concrete and brick sealed with taror equivalent material may be employed as a surface dressing for theplywood. In this connection, the terms bonded aggregate refers to theYuse of cement for binding the aggregate as well as bituminous or othersuitable agents.

In the construction of roadways and pavements as disclosed by thsinvention, comprising embedded plywood slabs, a resilient highway isprovided which is exceedingly durable and is considerably less expensiveto build than the convention-al hard surface roads.

It is understood, of course, that this invention is not limited to theexact details of construction since obvious modications may be made bypersons skilled in the art Within the scopevof the disclosure andappended claim.

- Having thus fully described by invention, what I claim asnew anddesire to secure by Letters Patent is:

An improved roadway or pavement construction comprising a roadbedsurface having a Waterproof coating thereover, a hard road foundationsurface layer laid thereon, a waterproof coating disposed oversaid hardfoundation surface, a cushion layer of sheet material laid over saidwaterproof coating, cross-grained plywood slabs disposed on said cushionlayer, and a waterproof road surface dressing cover layer appliedoverthetop and side surfaces of said plywood, said plywood being thoroughlysealed against contact with water.

CLARENCE U. GRAMELSPACHER.

